Process and apparatus for producing wooden pan-shaped bodies



y 1933- G. 'SCHLESINGER I 1,909,428

PROCESS AND APPARATUS FOR PRODUCING WOODEN PAN SHAPED BODIES Filed Oct. 19, 1951 INVENTOR Patented May 16, 1933 UNITED STATES TION OF SWITZERLAND PATENT orries .GEORG soHLnsINGER, 0F BERLIN-CHARLOTTENBURG, GERMANY, ASSIGNOR T0 AKTInN- GESELLSGHAFT' Fun ,I-IOLVZVEREDLUITG, or zn mon,

SWITZERLAND, a CORPORA- PROCESS AND ArPARA'rUs FOR rnonu'oiuewoonnn PAN-SHAPED BODIES Application filed October 19, 1931, Serial No.

The present-invention relates to anovel method of producing cup-shaped or panshaped bodies, for instance flanged bottoms or bases, from blanks which consist of one or more layers of wood or similar materials and which are treated in dies or other forming devices. It is very hard to form a sharp ly marked flange or rim on bodies of this kmd in dies and at the same time to impart suiiicient strength, tightness and permanence of shape. The ditficulties are particularly great when the bodies are made from wood and are due to the lack of homogeneity of the wood from which the single-layer or multiple-layer blanks are obtained, and to the'fact that the thickness of the blanks is not uniform, since the individual veneers, which are produced by cutting or splitting and from which the multiple-layer blank is made, are never of same thickness throughout. Further difiiculties arise through the tendency of the i wood to shrink, and particularly to grow thinner, when the layers arepressed together.

The process according to the present inven tion, by means of. which the aforesaid'difficulties are eliminated, consists in exertinga pressure on'the rim or edge of the'blank when the same 'is forced into the die, This pressure is suitably distributed over substantially the entirefedgeof the blank. A It will be evident from what issaid above, that the invention is specially advantageous when the material to be treated is wood. The invention may however also be used with great advantage for producing pan-shaped or cup-shaped bodies from other materials, for instance from paper, papiermach, carton, wood pulp, cellulose, artificial cellulose, leather, starchedfabric fiber, rubber, vulcanite, artificial resin and the like.

The invention is usually practised in such manner that, during the transformation or forming procedure, which is performed by means of a plunger that drives the blank into i a suitable opening, pressure is exerted on the free edge of the blank and particularly on that part of the edge in which the fibers are tangential. This pressure prevents in the turned over or bent rim the tearing apart of the fibers, which are then strained in a direc- 569, 574,' and in Germany November 26, 193d.- I

tion transverse to their length. Whennon fibrous material is treated the pressure'prevents the formation of cracks and crevices. The pressure on the free edge of theblank may be maintained for the entire duration of the'moulding of'the blank in the'die. It is however also possible (especially with wood of higher transverse strength), to delaythe application of. pressure to thef e'dge of the blank until the edge has been turned iupin the die, i. e. as soon as the blank is fully seated therein.

' .In the final position the die iscompletely closed and'by means of the downwardly directed pressurefthe edge of the rim is compressed until it isrendered completely smooth. a I

An apparatus for performing the process according tothe'invention is shownschematically in the accompanying drawing. Fig. 1 shows a .die with a plungerabuts ting against the blank. Fig. 2 shows the same device with the rim of the blank partway inthe cylindri- 75 cal portion of the die. Fig. 3 shows the same device with the plunger'entering the die. 1

Fig. 4 shows-the plunger and the blank in final position.

Fig. 5 isa sectional viewv taken on the line A'B in Fig. 1. i 1

Fig. 6 is a sectional view taken on the line CD in Fig. 4; Fig. 7 shows a detail. The invention 'will now be described in connection withthe producing of cup-shaped or pan-shaped wooden articles i In Figs. 1 to 7 1 denotes ablank con sisting of several superimposed layers of wooden veneer and intermediate layers of glue. Theblank rests initially on the top face 2 of the die' 3, which has a conical entrance inlet t anda cylindrical innerrecess or'forming chamber 5. The piston6 of the apparatus" at the bottom of the forming chamber 5 is a counter pressure piston and isadapted to be raised and lowered and is used as a seat during the form'ing'op eration and as an ejector of'the finished ar'- ticle. 7 is the main plunger which is'equipped' with a ring consisting of projecting segments 13. In the embodiment of the invention here shown the ring comprises siX segments. The segments 13 are arranged in the plunger 7 in such a manner that they form a continuous circle at the end of the pressure stroke of the plunger 7 (Figs. 4 and 6). At the beginning of the working stroke (Figs. 1 and 5) the segments project radially outward to such an extent that the upwardly bending wooden edges of the blank 1 are subjected to a pressure from above. The upwardly bending rim is thus brought safely under the segments and engages on the lower surface of same during the forming operation.

The segments are compressed by means of the inside conical surface 4, which during the sliding movement of the blank into the die 3 exerts the required inwardly directed radial pressure. In the position of Fig. 2 the segments 13 engage the edge of the rim and in the further depression of the plunger to the position of Fig. 3, the edge of the rim is crowded inward. As will be seen from Fig. 7 the segments 13 are forced outward by means of springs 14 and this movement is limited by the heads of the stop screws 15. In the final position the segments form a complete ring which entirely closes the chamber 5 and keeps the entire enclosed wooden mass under pressure.

'I claim:

1. The method of forming out of a blank of wood, a body having a bottom with a surrounding rim, comprising the forcing of said blank into a die chamber so as to turn up the peripheral portion thereof and thus produce the rim and the exertion of pressure upon the edge of said rim over the circumference of same.

2. The method of forming out of a wood blank 21. pan-shaped body having a bottom and a surrounding rim comprising the forcing of said'blank into a die to bend up the peripheral portion of the blank and produce the rim, the contraction of the rim and the exertion upon the edge of the rim of pressure over the entire circumference thereof.

3. An apparatus comprising a die having a forming chamber, a plunger to enter said die and force a blank into the forming chamber to bend up the peripheral portion thereof in the shape of a rim and means projecting from the periphery of the plunger against which the edge of the rim is' crowded in in the course of the forming operation.

4. An apparatus comprising a die having a forming chamber and plunger to enter said chamber and force a blank thereinto to bend the peripheral portion of the blank into the shape of a rim and a pressure ring carried by the plunger against which the edge of the rim is crowded in in the course of the form ing operation.

5. An apparatus comprising a die having a forming chamber, the entrance to which is of gradually decreasing diameter, a plunger to enter said chamber and force a wooden blank thereinto, the peripheral portions of the blank being bent up by the interior surface by the entrance to said chamber into the shape of a rim and means projecting from the periphery of the plunger adapted to enter the die and against which the edge of the rim is crowded in in the course of the forming operation.

6. An apparatus comprising a die having a forming chamber with a contracting entrance opening, a plunger to enter the die and force into the forming chamber a blank so that the peripheral portion thereof is bent and con tracted by the interior surface of the entrance to the chamber and given the shape of a rim as the blank enters said chamber and a yieldable ring encircling the plunger against which the edge of the rim is crowded in, in the course of the forming operation.

7. An apparatus comprising a die having a forming chamber with a contracting entrance opening, a plunger to enter the die and force into the forming chamber a blank so that the peripheral portion thereof is bent and contracted by the interior surface of the entrance to the chamber and given the shape of a rim as the blank enters said chamberand a yieldable ring encircling the plunger against which the edge of the rim is crowded in, in the course of the forming operation, said ring comprising segments and the plunger having a groove to receive the said segments. 7

8. An apparatus comprising a die having a forming chamber with a contracting inlet opening, a plunger to enter the die and force thereinto a wooden blank, a peripheral portion of which is bent in said opening in the shape of a rim, a pressure ring carried by the plunger in position to enter said opening and against which the edge of the rim is crowded in as the blank is forced into the forming chamber, said plunger having a circumferential groove to receive said ring, the latter be ing in the form of a number of grooved segments, yieldable means for urging said segments readily outward and stops to arrest the segments in their outermost positions.

In testimony whereof I affix my signature.

GEORG SCHLESINGER. 

